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L. MEISTER Sept. 25, 1945.

APPARATUS FOR INSPECTING FLASH HOLES IN PRIMER TUBES Filed July 20, 1942 I Let: Meilscar Q g 7M M Patented Sept. 25, 1945 APPA'EEJS IFQR WSPE IN PRIRMR TUBES Leo Meister, 1 r

Application July 20, 1942, Serial No. 451,679

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 3 Claims.

The invention described herein may be manuiactured and used by or for the Government for exterior of primer tubes in the course of theirmanufacture.

Another object of this invention is to provide apparatus whereby inspection oi primer tubes after waterproofing and drying is no longer re quired; inspection is necessary in accordance with prior art practise.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodi ment as shown in the accompanying drawing in which:

Figure 1 shows my article for inspecting tubes.

Figure 2 shows the primer tube which is to be inspected by using the article of Figure 1.

Figure 3 shows the article of Figure 2 assembled on the article of Figure 1 with a light source in testing position.

In Figure 1 is shown an elevational view of my rotatable body having a cylindrical and partially tubular body portion it, a light receiving and diverting head ll comprising cone Hand cone H, a cylindrical projection ll adapted to receive a spindle it which is engaged by an element of a turning mechanism, forinstance, the chuck of a drill press or the like (not shown), and a polished metal plug l6 which serves as a light reflector and dirt stop.

The body A is essentially of the plastic material, methyl methacrylate, commonly referred to as "Lucite" and Plexiglass;" and, the mutually inverted conical portions 12, it in forming head II, have critical dimensions. The truncated conical portion i2 has its outer boundary line projecting at an angle in the range of 40 to 42 degrees from the axis of cylinder I and the inverted conical portion l3 joins the conical portion 13 at an angle of ninety degrees as indicated in Figure 1. 1

It is understood that other plastic materials similar to Lucite or Plexig1ass" may be used so long as the index of refraction of the same is comparable, and in applicants particular arrangement it is desirable that the material have a low heat conductivity.

Spindle I5 is fastened in cylindrical projection I i by means similar to screw threads Ma, and it is noted that spindle l5 extends into the body of the thermoplastic through conical portion 53 and into truncated conical portion I 2.

The outer surface of conical portion i3 is polished and the outer surface of conical portion i2 is preferably coated with an opaque material such as black paint.

The cylindrical body portion its having hollow portion ma closed by polished metal plug it has its outer surface finished to appear as the finish of ground glass. 1

In the manufacture of primer tubes it in the production of ammunition it is important that the tube iiash holes itd be filled with a compound, for example tar, whereby the interior of the tube is sealed against humidity, etc., but said compound is cleared away by detonation of powder within tube It. This invention in its narrcwest sense relates to the inspection of the effectiveness of the compound sealing operation. The compound sealing operation consists in lining the primer tube it with paper (not shown) and then coating the flash holes its with a com pound similar to tar; imperfect coating after this operation results in holes allowing transmission of light as shown in Figure 2.

After the sealing operation the primer tube is placed on the body portion it which is adapted to snugly receive the primer tube it and then the body portion it is turned by rotary motion imparted to spindle i5. Light is projected on and perpendicular to the polished .outer surface of cone l3 from a suitable light source and as the light passes through the imperfectly coated flash holes id in the primer holes, due to the persistency of vision of the observer, light streaks Itb will appear; the observer may then apply an additional corrective coating of compound to those spots which cause light streaks itb. As the tube v y it is rotated the tar in the flash holes will cause is led downwardly without substantial loss to the tubular portion of body Hi from where it is projected out of defective flash holes I8d.

I claim:

1. An article of manufacture comprising a transparent cylindrical body having a truncated g conical portion of transparent material coaxially joined thereto, a second conical portion, also of transparent material, coaxially mounted on the base of the first conical portion in inverted relationship thereto, with the outer boundary line l0 thereof meeting the outer boundary line of the joined conical portion, the cylindrical body having a ground surface and being tubular at the end opposite the Joined end, and a metal plug closing relationship thereto, with the outer boundary line thereof meeting the outer boundary line or the joined conical portion at a ninety degree angl said first-mentioned conical portion being coated with opaque material, and said cylindrical body having a ground surface.

3. An article of manufacture comprising a transparent cylindrical block of methyl methaerylate having a frusto-conical portion coaxially joined thereto, the outer boundary line or said conical portion making a projected angle of fortytwo degrees with said axis, a second irusto-conicai portion coaxially mounted on the base of the first conical portion in inverted relationship the tubular end and having a polished surface iathereto, with the outer boundary line thereof facing the interior of the body.

2. An article of manufacture comprising a transparent cylindrical body having a truncated;

transparent conicalportion coaxially Joined meeting the outer boundary line of the Joined conical portion at a ninety degree angle, said firstmentioned conical portion being coated with opaque material, said cylindrical body having a thereto, the outer boundary line 01' said conical 20 ground outer surface and being tubular with the portion making a projected angle of forty-two degrees with said axis, a second conical portion,

also of transparent material, coaxially mounted on the base of the first conical portionin inverted inner walls polished, and a p lished metal plug inserted in the tubular portion oi the cylindrical My:

LEO MEISTER. 

